Method for spinning viscose



June 13, 1950 N. DRISCH ErAl. 2,511,699

METHOD FOR SPINNING vIscosE Filed Nov. 4, 1948 1N VEN TORs /V/ (GLAS e/.sc H

ROBERT PR/oc/ A YTNEY Patented June 13, 1950 UNITED STAT Es PATENT OFFICE- I 2,511,699-y Y METHOD FOR SPINNING VISCOSE Nicolas Drisch and Robert Priou, Paris, France, assignors to Comptoir des TextilesfArtifciels, a corporation of France Application November 4, 19/4s,"seria1No. 58,248 In France November 10, 1947 4 Claims.

This invention relates to a method for spinning viscose to be used in the manufacture of rayon, iibranne, erin, lame, and the like, and has for an object to provide a method of the above type wherein the rate of spinning can be considerably increased, and the filament can be further drawn out, without rupturing or parting the strands.

Another object is to provide a method of the above type having novel and improved characteristics.

Other objects and advantages will be apparent as the nature of the invention is more fully disclosed.

In accordance with the present invention the filaments from the spinneret are passed through a straight tube of suitable diameter which is immersed in the bath. The tube begins at a point a short distance beyond the spinneret and is positioned in axial alignment with the feed mechanism so that the filaments proceed in a straight line from the spinneret to the feed mechanism. The tube is of a diameter such that the liquid is entrained therein and iiows therethrough due solely to the motion of the filaments.

The invention will be better understood by referring to the following description, taken in connection with the accompanying drawing in which the ligure is a diagrammatic representation of one form' of apparatus for carrying out the invention.

In the example shown, a spinneret tube I bearing a spinneret 2 is immersed in a coagulating bath 3. A pump shown schematically at I feeds viscose to the spinneret at a controlled rate.

The filament is coagulated at the surface by the bath and then enters a glass tube 4, thus drawing the bath through it. The filament makes one or more turns around a feed roller 5, whereupon it continues to the roller 6 which revolves at a higher circumferential speed than the roller for drawing out the filament. This elongation of the filament may be facilitated by immersion thereof in a bath of hot water between the rollers.

In the absence of the tube 4, all other things being equal, the filament frequently breaks or is greatly impaired by the presence of broken strands which are partially rolled up on the second roller B. With the addition of the tube 4 these difficulties are practically eliminated, and the degree of elongation may even be increased to 64% to 70%. The filament obtained by this process possesses excellent mechanical properties.

Generally speaking, it is advantageous to locate the mouth of the tube 4 as close as possible to the spinneret 2. The only limitation is the necessity of preventing contact between the fine strands, which are still very fragile, and the opening or wall of the tube. It is essential to center the latter accurately around the straight line connecting the center of the spinneret and the point where the filament passes onto the first feed roller 5, or the point of convergence on the first guide, if any, in advance of the feed roller.

The bath is drawn into the tube by the filaments and shortly reaches a condition of equilibrium which depends primarily on the speed and. weight of the thread and on the diameter of the tube. In general, a larger diameter should be used for a thicker filament.

As a specific example, the spinneret 2 may have holes and may be immersed in a coagulating bath containing g. of sulfuric acid, 260 g. of sulfate of soda and 40 g. of zinc sulfate per liter heated to 550 C. The pump l0 may feed the viscose to the spinneret at a rate corresponding to 200 denier. The tube may be 60 cm. in length, 1 em. in diameter and may begin 2 or 3 cm. from the spinneret.

A more concentrated or more viscous bath requires a larger tube. This is the case, for example, in sulfuric acid baths in excess of 53 C., which require tubes of e. g. 20 to 25 mm. It is difficult to place limits on the tube diameters, but it is desirable to use tubes suiciently small to force the circulation, which should tend to a speed corresponding to that of the filament.

The feed roller 5 may have a circumferential velocity adapted to draw the filament through the tube 4 at a rate of 100 meters per minute. The circumferential speed of the feed roller 8 may be of the order of meters per minute to produce an elongation of 50% or may be such as to produce an elongation of from 64% to 70%. The filament between the rolls 5 and 6 may be immersed in a Water bath at 85 C. to 90 C. to facilitate the drawing operation.

The method above set forth has been found to produce improved results, increasing the rate of feed and elongation, land reducing the tendency of the strands to break. Of course, the invention is not restricted to the mode of execution nor to the dimensions and quantities indicated above, which have been selected solely by way of example.

W-hat is claimed is:

1. The method of spinning viscose for the manufacture of rayon and the like which comprises ejecting the viscose from a spinneret into a coagulating bath and drawing the filaments in a straight line through a straight cylindrical open-ended tube of small diameter immersed at both ends in said bath and centered with respect to said spinner-et, to keep the filaments out of contact with the inner wall of the tube, and inducing a flow of the bath through said tube solely by the axial motion of the filament bundle through the tube.

2. The method set forth in claim 1, in which the lament bundle is drawn through said tube l0 by a rst feed roller and is then stretched 5070% by passing it over a second feed roller of higher peripheral speed.

3. The method set forth in claim 2, in which the feed rolls feed the filament at rates of 100 meters per minute and at least 150 meters per minute respectively.

4. The method set forth in claim 2, in which the filament is passed through a heated water bath between said rollers.

NICOLAS DRISCH.

ROBERT PRIOU.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Namel Date 2,243,116l Ostermann May 27, 1941 2,440,057 v Millhiser Apr. 20, 1948 

1. THE METHOD OF SPINNING VISCOSE FOR THE MANUFACTURE OF RAVON AND THE LIKE WHICH COMPRISES EJECTING THE VISCOSE FROM A SPINNERET INTO A COAGULATING BATH AND DRAWING THE FILAMENTS IN A STRAIGHT LINE THROUGH A STRAIGHT CYLINDRICAL OPEN-ENDED TUBE THE SMALL DIAMETER IMMERSED AT BOTH ENDS IN SAID BATH AND CENTRED WITH RESPECT TO SAID SPINNERET, TO KEEP THE FILAMENTS OUT OF CONTACT WITH THE INNER WALL OF THE TUBE, AND INDUCING A FLOW OF THE BATH THROUGH SAID TUBE SOLELY BY THE AXIAL MOTION OF THE FILAMENT BUNDLE THROUGH THE TUBE. 